G/flex 650 is a toughened, versatile, liquid epoxy for permanent waterproof bonding of fiberglass, ceramics, metals, plastics, damp and difficult-to-bond woods. With a modulus of elasticity of 150,000 PSI, it is a bit more flexible than standard epoxies and polyester, but much stiffer than adhesive sealants. This gives it the ability to make structural bonds that can absorb the stress of expansion, contraction, shock, and vibration. It is ideal for bonding dissimilar materials. It can be modified with WEST SYSTEMS fillers and additives and used to wet-out fiberglass tapes and fabrics. Mixed at a 1:1 ratio, this 2-part epoxy gives you 46 minutes of pot life at 72°F and an open (working) time of 60-75 minutes. It reaches an initial cure in 3 to 4 hrs and a workable cure in 7-10 hours.